ORCS. Den skill (increase towers firerate):
* Gold Vault - Adds gold in the beginning of a mission.
* Height Advantage - Towers on HIGH GROUND tiles cause more damage.
* Mining - Adds +1 gem in a mission.
* Cut Down Study - CUT OUT spell costs mana less.
* Cut Down Mastery - Gives gold when you CUT OUT a forest.
* Marksmanship - Adds critical strike to Orcish Den and Hunter's Den.
* Bounty Hunting - Adds gold for destroying enemies.
* Warchief - Decrements upgrade cost of dens and dens get more experience.
* Poison Mastery - Adds poison cloud to dens.

UNDEAD. Crypts skill (increase towers range):
* Mana Stock - Adds mana in the beginning of a mission.
* Mana Pool - Adds to maximum mana.
* Soul Vault - Adds +1 charge for crypts.
* Frenzy Study - FRENZY spell costs mana less.
* Frenzy Mastery - Adds fire rate of towers when FRENZY spell is active.
* Mind Control - Adds fear of Chilling Crypt and Fearful Crypt.
* Mana Extraction - Adds mana generation rate.
* Lich King - Decrements upgrade cost of crypts and crypts get more experience.
* Ice Mastery - Adds freeze to crypts.

DEMONS. Temple skill (increase towers damage):
* Basic Training - Towers get more experience.
* Scorching Treasure - Enemies loses HP per second if they carry gem.
* Adoration - Adds +20 mana when you build temple.
* Meteor Study - METEOR spell costs mana less.
* Meteor Mastery - Adds damage of METEOR spell.
* All-seeing Eye - Adds radiance to Evileye Temple and Beholder's Temple.
* Return Portal - If a gen is lying on ground N minutes it returns to the cave.
* Demon Lord - Decrements upgrade cost of temples and temples get more experience.
* Fire Mastery - Adds blaze to temples.